In writing “Connie and Carla,” Nia Vardalos should have cut right to the chase and named the characters Lucy and Ethel. The wacky shenanigans, the outrageous costumes, the lunkish menfolk, the celebrity guests — this is “I Love Lucy,” right? It’s about as funny, too, and I don’t really mean that as a compliment.

Vardalos, who also wrote and starred in “My Big Fat Greek Wedding” and thus has impossible expectations to meet here, plays vivacious Connie to Toni Collette’s hesitant Carla (or Lucy to her Ethel, but I’ll stop belaboring that point). They’re a pair of hapless Chicago gals with a showtune-oriented cabaret act that they’ve so far only been able to perform in airport lounges, though they have their sights set on dinner theater. One night they not only witness a mob hit, but inadvertently run off with some of the mob’s cocaine, too, thus making themselves targets if ever there were.

Rather than go to the police, they flee to Los Angeles — West Hollywood, specifically, where both women’s utter lack of both common sense and ordinary gaydar means they don’t realize all the men around them are homosexual. But it works to their advantage, because the nightclub near their new apartment (yes, they rent an apartment … I guess they’re planning to live in L.A. forever, rather than figure out a way to handle the mobsters) is holding auditions for new drag queens to headline its cabaret nights. Since Connie and Carla aren’t very pretty, all they have to do is tart themselves up a bit and dress in gaudy clothing and they’ll look like men dressed as women. Plus, they can actually sing their numbers, whereas most drag queens only lip-synch. It’s the perfect ruse!

Their act is a huge hit with the club’s clientele of young gay men and straight women. Connie and Carla’s onstage mantra of accepting yourself even if you’re not beautiful and in perfect shape resonates with the audience (even though most of them ARE beautiful and in perfect shape, making their endorsement of that philosophy seem a little hollow), and the girls are finally living their dream. They even attract the attention of their idol, Debbie Reynolds (who makes a cameo that is embarrassing in its uselessness.) So what if they have to make themselves up as drag queens 24 hours a day?

In keeping with the “Some Like It Hot” homage (or ripoff, depending on how you look at it), Connie falls for a guy named Jeff (David Duchovny), the brother of one of the club’s backup drag queens. Jeff thinks Connie is a guy who happens to dress in drag all the time, though, and since he’s straight, men have no appeal for him, regardless of how they’re dressed.

Carla, meanwhile, is nervous about the success she and Connie are having at the club. If they get TOO famous, she’s worried the gangsters will find them. As it is, the bad guys have sent an underling (Boris McGiver) to all the dinner theaters in the country, since that’s where Connie and Carla had made it known they were aspiring to go, hoping to find them but finding only one production after another of “Mame.”

The film’s first act is too preposterous to accept, and I don’t mean the girls’ silly plan of posing as drag queens. I mean little things like not going to the police, not recognizing a room full of gay men when they see one, thinking if they twist the tape in a cassette of accompaniment music it will lower the key — stupid things like that. If this were “Dumb and Dumber,” I’d buy it. But these characters aren’t supposed to be imbeciles. They’re supposed to be ordinary women, but the screenplay conspires against them.

However, once the movie (directed by Michael Lembeck, of “The Santa Clause 2”) settles into its groove, it’s a moderately enjoyable little comedy, albeit a predictable and sloppy one.

Toni Collette, who is best-known for more dramatic roles in films like “The Sixth Sense” and “About a Boy,” here uses the self-deprecating wit that served her so well in earlier works such as “Muriel’s Wedding,” “Emma” and “Clockwatchers.” Her face has character, and she is unafraid to use it to make herself look absurd.

Nia Vardalos, on the other hand, hasn’t quite come into her own as an actress. Nia is likable in her magazine interviews and TV appearances, but Connie isn’t quite — or rather, she might be, if Vardalos were a good enough actress to convince us she’s real. As it is, I kept thinking about the way Connie was steamrolling over Carla’s free will by forcing her into things, and the idiotic way she kept drooling over Jeff. Had Collette been paired with a comic equal, things might have been different.